I don’t think the troops we have in SK are near enough to launch a war against NK, which you also suggest. I don’t think we would have SK’s help. SK will focus on defensive measures to protect their people and to continue diplomacy with Kim. I don’t think Kim wants war. Take the US out of the equation and it seems to me that the rest of the world would do a deal with him and look for more economic, diplomatic and cultural openings to moderate the regime from within. Kim might be ok with that. His biggest concern is the US obsession with regime change. With the US looking weak and isolated, other countries like China would have a pretty good chance of rallying the int’l community against war.
But Trump and the hardliners are not without cards either. They would fall back on Bush’s axis of evil to argue that Kim’s regime is an abomination to humanity and must be replaced. He’d have the support of the GOP and GOP leaning Indies for such an argument.